package com.techshine.common.page;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Properties;

import javax.xml.bind.PropertyException;

import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.executor.ExecutorException;
import org.apache.ibatis.executor.statement.BaseStatementHandler;
import org.apache.ibatis.executor.statement.RoutingStatementHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.mapping.ParameterMode;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.plugin.Intercepts;
import org.apache.ibatis.plugin.Invocation;
import org.apache.ibatis.plugin.Plugin;
import org.apache.ibatis.plugin.Signature;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.property.PropertyTokenizer;
import org.apache.ibatis.scripting.xmltags.ForEachSqlNode;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.type.TypeHandler;
import org.apache.ibatis.type.TypeHandlerRegistry;

import com.techshine.util.ReflectHelper;
import com.techshine.util.Tools;

/**
 * 
* 类名称：PagePlugin.java
* 类描述： 
* @author FH
* 作者单位： 
* 联系方式：qq313596790
* 创建时间：2014年7月1日
* @version 1.0
 */
@Intercepts({@Signature(type = StatementHandler.class, method = "prepare", args = {Connection.class})})
public class PagePlugin implements Interceptor {
    
    private static String dialect = ""; //数据库方言
    
    private static String pageSqlId = ""; //mapper.xml中需要拦截的ID(正则匹配)
    
    public Object intercept(Invocation ivk)
        throws Throwable {
        // TODO Auto-generated method stub
        if (ivk.getTarget() instanceof RoutingStatementHandler) {
            RoutingStatementHandler statementHandler = (RoutingStatementHandler)ivk.getTarget();
            BaseStatementHandler delegate = (BaseStatementHandler)ReflectHelper.getValueByFieldName(statementHandler, "delegate");
            MappedStatement mappedStatement = (MappedStatement)ReflectHelper.getValueByFieldName(delegate, "mappedStatement");
            
            if (mappedStatement.getId().matches(pageSqlId)) { //拦截需要分页的SQL
                BoundSql boundSql = delegate.getBoundSql();
                Object parameterObject = boundSql.getParameterObject();//分页SQL<select>中parameterType属性对应的实体参数，即Mapper接口中执行分页方法的参数,该参数不得为空
                if (parameterObject == null) {
                    throw new NullPointerException("parameterObject尚未实例化！");
                }
                else {
                    Connection connection = (Connection)ivk.getArgs()[0];
                    String sql = boundSql.getSql();
                    //String countSql = "select count(0) from (" + sql+ ") as tmp_count"; //记录统计
                    String countSql = "select count(0) from (" + sql + ")  tmp_count"; //记录统计 == oracle 加 as 报错(SQL command not properly ended)
                    PreparedStatement countStmt = connection.prepareStatement(countSql);
                    BoundSql countBS = new BoundSql(mappedStatement.getConfiguration(), countSql, boundSql.getParameterMappings(), parameterObject);
                    setParameters(countStmt, mappedStatement, countBS, parameterObject);
                    ResultSet rs = countStmt.executeQuery();
                    int count = 0;
                    if (rs.next()) {
                        count = rs.getInt(1);
                    }
                    rs.close();
                    countStmt.close();
                    //System.out.println(count);
//                    Page page = null;
//                    if (parameterObject instanceof Page) { //参数就是Page实体
//                        page = (Page)parameterObject;
//                        page.setEntityOrField(true);
//                        page.setTotalResult(count);
//                    }
//                    else { //参数为某个实体，该实体拥有Page属性
//                        Field pageField = ReflectHelper.getFieldByFieldName(parameterObject, "page");
//                        if (pageField != null) {
//                            page = (Page)ReflectHelper.getValueByFieldName(parameterObject, "page");
//                            if (page == null) {
//                                page = new Page();
//                            }
//                            page.setEntityOrField(false);
//                            page.setTotalResult(count);
//                            ReflectHelper.setValueByFieldName(parameterObject, "page", page); //通过反射，对实体对象设置分页对象
//                        }
//                        else {
//                            throw new NoSuchFieldException(parameterObject.getClass().getName() + "不存在 page 属性！");
//                        }
//                    }
                    
                    
                    ReflectHelper.setValueByFieldName(parameterObject, "count", count); //通过反射，对实体对象设置分页对象
                    //String pageSql = generatePageSql(sql, page);
                    int  page= (int)ReflectHelper.getValueByFieldName(parameterObject, "page");
                    int limit=(int)ReflectHelper.getValueByFieldName(parameterObject, "limit");
                    String pageSql = generatePageSql(sql,page,limit);
                    ReflectHelper.setValueByFieldName(boundSql, "sql", pageSql); //将分页sql语句反射回BoundSql.
                }
            }
        }
        return ivk.proceed();
    }
    
    /**
     * 对SQL参数(?)设值,参考org.apache.ibatis.executor.parameter.DefaultParameterHandler
     * @param ps
     * @param mappedStatement
     * @param boundSql
     * @param parameterObject
     * @throws SQLException
     */
    private void setParameters(PreparedStatement ps, MappedStatement mappedStatement, BoundSql boundSql, Object parameterObject)
        throws SQLException {
        ErrorContext.instance().activity("setting parameters").object(mappedStatement.getParameterMap().getId());
        List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
        if (parameterMappings != null) {
            Configuration configuration = mappedStatement.getConfiguration();
            TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();
            MetaObject metaObject = parameterObject == null ? null : configuration.newMetaObject(parameterObject);
            for (int i = 0; i < parameterMappings.size(); i++) {
                ParameterMapping parameterMapping = parameterMappings.get(i);
                if (parameterMapping.getMode() != ParameterMode.OUT) {
                    Object value;
                    String propertyName = parameterMapping.getProperty();
                    PropertyTokenizer prop = new PropertyTokenizer(propertyName);
                    if (parameterObject == null) {
                        value = null;
                    }
                    else if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {
                        value = parameterObject;
                    }
                    else if (boundSql.hasAdditionalParameter(propertyName)) {
                        value = boundSql.getAdditionalParameter(propertyName);
                    }
                    else if (propertyName.startsWith(ForEachSqlNode.ITEM_PREFIX) && boundSql.hasAdditionalParameter(prop.getName())) {
                        value = boundSql.getAdditionalParameter(prop.getName());
                        if (value != null) {
                            value = configuration.newMetaObject(value).getValue(propertyName.substring(prop.getName().length()));
                        }
                    }
                    else {
                        value = metaObject == null ? null : metaObject.getValue(propertyName);
                    }
                    TypeHandler typeHandler = parameterMapping.getTypeHandler();
                    if (typeHandler == null) {
                        throw new ExecutorException("There was no TypeHandler found for parameter " + propertyName + " of statement "
                            + mappedStatement.getId());
                    }
                    typeHandler.setParameter(ps, i + 1, value, parameterMapping.getJdbcType());
                }
            }
        }
    }
    
    /**
     * 根据数据库方言，生成特定的分页sql
     * @param sql
     * @param page
     * @return
     */
//    private String generatePageSql(String sql, Page page) {
//        if (page != null && Tools.notEmpty(dialect)) {
//            StringBuffer pageSql = new StringBuffer();
//            if ("mysql".equals(dialect)) {
//                pageSql.append(sql);
//                pageSql.append(" limit " + page.getCurrentResult() + "," + page.getShowCount());
//            }
//            else if ("oracle".equals(dialect)) {
//                pageSql.append("select * from (select tmp_tb.*,ROWNUM row_id from (");
//                pageSql.append(sql);
//                //pageSql.append(") as tmp_tb where ROWNUM<=");
//                pageSql.append(") tmp_tb where ROWNUM<=");
//                pageSql.append(page.getCurrentResult() + page.getShowCount());
//                pageSql.append(") where row_id>");
//                pageSql.append(page.getCurrentResult());
//            }
//            return pageSql.toString();
//        }
//        else {
//            return sql;
//        }
//    }
    private String generatePageSql(String sql, int page,int limit) {
        if (limit>0&&page>0) {
            StringBuffer pageSql = new StringBuffer();
            if ("mysql".equals(dialect)) {
                pageSql.append(sql);
                pageSql.append(" limit " + ((page-1)*limit) + "," + limit);
            }
            else if ("oracle".equals(dialect)) {
                pageSql.append("select * from (select tmp_tb.*,ROWNUM row_id from (");
                pageSql.append(sql);
                //pageSql.append(") as tmp_tb where ROWNUM<=");
                pageSql.append(") tmp_tb where ROWNUM<=");
                pageSql.append(page + limit);
                pageSql.append(") where row_id>");
                pageSql.append(page);
            }
            return pageSql.toString();
        }
        else {
            return sql;
        }
    }
    public Object plugin(Object arg0) {
        // TODO Auto-generated method stub
        return Plugin.wrap(arg0, this);
    }
    
    public void setProperties(Properties p) {
        dialect = p.getProperty("dialect");
        if (Tools.isEmpty(dialect)) {
            try {
                throw new PropertyException("dialect property is not found!");
            }
            catch (PropertyException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        pageSqlId = p.getProperty("pageSqlId");
        if (Tools.isEmpty(pageSqlId)) {
            try {
                throw new PropertyException("pageSqlId property is not found!");
            }
            catch (PropertyException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
    
}
